For one couple the question was more precise...would guests commit to being there for the couple during good times - as well as bad, to help them through any difficult times in their relationship with honesty and integrity.
Of course guests will happily agree to offer this kind of unconditional support at the ceremony, but I wonder for how long does their commitment last? So often people disappear off the horizon when they realise friends' relationships are in difficulty. And if they do step in to help, they often take sides, which can cause the couples' problems to escalate.
Friends or family just being there to listen without judging and without taking sides, can be of great assistance so can the knowledge that no relationships are easy and difficult times are part and parcel of life.
Specially trained professional counsellors can also help - and it's worth remembering that a few sessions early on may avoid more serious problems later on.
All too often we seek help only when in dire crisis, hospitals when we're physically ill and counsellors or psychologists when we're at our wit's end.
The health of all relationships takes constant work - but's well worth putting in the effort - whether we are friends, family or part of a couple.